Along with the development of Internet technologies, Ethernet-based Layer2 Virtual Private Network (L2VPN) technologies are widely used. Virtual Private LAN Service (VPLS) technologies support one-to-multiple Media Access Control (MAC) forwarding.
In order to prevent loops caused by the MAC forwarding, some limitations are configured for the networking of the VPLS. For example, in a backbone network, full mesh connection of Pseudo wires (PWs) may be established among all Provider Edges (PEs). The PE accessing to the network may use Hierarchy of VPLS (H-VPLS) to prevent the rapid expansion of the full mesh connection scale.